Propylene resin composition and automobile trim member

ABSTRACT

PCT No. PCT/JP97/02108 Sec. 371 Date Aug. 19, 1998 Sec. 102(e) Date Aug. 19, 1998 PCT Filed Jun. 19, 1997 PCT Pub. No. WO97/49765 PCT Pub. Date Dec. 31, 1997A propylene-based resin composition comprising (A) from 42 to 95% by weight of a propylene-based resin having an isotactic pentad fraction of at least 95%, (B) from 1 to 10% by weight of an ethylene-C3-C18  alpha -olefin copolymer having a density of from 0.850 to 0.875 g/cm3 and a melt index of from 0.01 to 25 g/10 min, and prepared in the presence of a metallocene catalyst, (C) from 2 to 18% by weight of a high-density polyethylene having a density of from 0.93 to 0.97 g/cm3 and a melt index of from 0.5 to 10 g/10 min, and (D) from 2 to 35% by weight of talc, the total of the components (B) and (C) being from 3 to 23% by weight.

TECHNICAL FIELD

The present invention relates to propylene-based resin compositions andautomobile trim members, and more precisely, to propylene-based resincompositions having good impact resistance, good scratch-whiteningresistance and good weld appearance with little uneven gloss and toautomobile trim members made by injection-molding of the composition.

BACKGROUND ART

Non-coated automobile trim members are being popularized for the purposeof reducing the production costs, for which there is increasing a greatdemand for materials having good characteristics of outward appearanceand a quiet feel while preventing light reflection. In addition, therequirements of safe and economical materials are being on a higherlevel, and inexpensive materials with good impact resistance aredesired.

As the materials of automobile trim members, much used are inexpensive,popular propylene-based resins. It is known that addition ofstyrene-based elastomers to propylene-based resins is effective forimproving the impact resistance (room temperature Izod impact strength)of the resins. However, styrene-based elastomers are expensive and areproblematic in that the moldings comprising them shall have an increaseddegree of surface gloss. Moreover, adding a large amount of rubbercomponents to propylene-based resins for the purpose of improving theimpact resistance of the resins is further problematic in that thescratch-whitening resistance of the resin moldings is poor.

On the other hand, known are molding materials having goodlow-temperature impact resistance. For example, disclosed are resincompositions comprising a crystalline propylene-ethylene block copolymerand an ethylene-α-olefin copolymer as produced in the presence of ametallocene catalyst (see Japanese Patent Application Laid-Open (JP-A)Hei-7-145272, JP-A Hei-7-145298); resin compositions comprising apropylene-based resin and an ethylene-butene-1 copolymer having arelatively large butene-1 unit content (the copolymer is producedsubstantially in the presence of a metallocene catalyst) (see JP-AHei-6-192506, JP-A Hei-7-18151); and resin compositions comprising apropylene-based resin and an ethylene-octene-1 copolymer having arelatively large octene-1 content (the copolymer is producedsubstantially in the presence of a metallocene catalyst) (seeInternational Patent Application Laid-Open No. 94-6859).

Though having good low-temperature impact resistance, those resincompositions are still defective in that their moldings often haveuneven gloss and poor scratch-whitening resistance.

DISCLOSURE OF THE INVENTION

Given that situation, we, the inventors have made the present invention,and the object of the invention is to provide propylene-based resincompositions having good impact and scratch-whitening resistance andgood weld appearance with little uneven gloss and to provide automobiletrim members to be made by injection-molding of the composition. Themembers do not require coating, and are therefore economical.

The inventors have assiduously studied and, as a result, have found thata resin composition that comprises a propylene-based resin havingspecific properties to which are added a specific impact-resistantagent, a high-density polyethylene and talc can attain the object notedabove. On the basis of this finding, the present invention has beencompleted.

Specifically, the present invention provides, as the first invention(I), a propylene-based resin composition comprising (A) from 42 to 95%by weight of a propylene-based resin having an isotactic pentad fractionof at least 95%, (B) from 1 to 10% by weight of an ethylene-C₃ -18α-olefin copolymer having a density of from 0.850 to 0.875 g/cm³ and amelt index of from 0.01 to 25 g/10 min, and prepared in the presence ofa metallocene catalyst, (C) from 2 to 18% by weight of a high-densitypolyethylene having a density of from 0.93 to 0.97 g/cm³ and a meltindex of from 0.5 to 10 g/10 min, and (D) from 2 to 35% by weight oftalc, the total of the components (B) and (C) being from 3 to 23% byweight.

It also provides, as the second invention (II), a propylene-based resincomposition of the first invention (I) where the component (A) satisfiesthe following requirements (1) to (4). (1) The propylene-based resin of(A) comprises (a) from 70 to 98% by weight of a fragment insoluble inparaxylene at 23° C. and (b) from 2 to 30% by weight of a fragmentsoluble in paraxylene at 23° C. (2) The fragment (a) has a relaxationtime, τ, of from 0.01 to 0.35 seconds at an angular frequency, ω, of10°/sec as obtained through melt viscoelastometry, and has a molecularweight distribution index (PDI) of from 1 to 18, which is represented byω₂ /10ω₁ where ω₁ indicates an angular frequency at which the modulus ofstored elasticity, G', as obtained through melt viscoelastometry is2×10² Pa, and ω₂ indicates an angular frequency at which G' is 2×10⁴ Pa.(3) The fragment (b) has a limiting viscosity [η] (in decalin at 135°C.) of from 2.0 to 10 dl/g. (4) The ethylene unit content of (A) is from1 to 17% by weight.

The invention further provides automobile trim members to be produced byinjection-molding the propylene-based resin composition.

BEST MODES OF CARRYING OUT THE INVENTION

The properties of the propylene-based resin of the component (A) to bein the resin composition of the present invention are mentioned below.

In the first invention and the second invention, the propylene-basedresin of the component (A) must have an isotactic pentad fraction of atleast 95%. The isotactic pentad fraction as referred to herein can beobtained from the signals appearing in the methyl carbon region in the¹³ C-NMR spectral pattern of the resin. Propylene-based resins having anisotactic pentad fraction of smaller than 95%, if combined with theother components, produce resin compositions of which the stiffness andthe impact resistance are not well balanced and which has poorscratch-whitening resistance. Accordingly, the isotactic pentad fractionof the propylene-based resin of the component (A) is preferably at least96%.

In the second invention, the component (A), when fractionated inparaxylene at 23° C., comprises (a) from 70 to 98% by weight of aparaxylene-insoluble fragment and (b) from 2 to 30% by weight of aparaxylene-soluble fragment. Moldings comprising a propylene-based resinhaving a paraxylene-insoluble content of smaller than 70% by weight willhave low stiffness, uneven gloss in the creped area, and bad weldappearance, and are often colored unevenly, and flow marks are oftenformed on their surface; while those comprising a propylene-based resinhaving a paraxylene-insoluble content of larger than 98% by weight willhave poor impact resistance, bad weld appearance, and uneven gloss inthe creped area. In order that the moldings of the composition of theinvention may have well-balanced properties of good appearance, highstiffness, high impact resistance and even gloss, the insoluble contentof the component (A) is preferably from 75 to 93% by weight, morepreferably from 80 to 91% by weight.

The fractionation of the component (A) in paraxylene at 23° C. may beeffected by first completely dissolving the resin in paraxylene at 130°C. followed by cooling the resulting solution to be at 23° C., whereuponthe resin is fractionated into the soluble fragment and the insolublefragment.

In the second invention, the fragment (a) must have a relaxation time,τ, of from 0.01 to 0.35 seconds at an angular frequency, ω, of 10°/secas obtained through melt viscoelastometry. Moldings comprising thecomponent (A) of which the fragment (a) has a relaxation time, τ, oflonger than 0.35 seconds will have bad weld appearance and uneven glossin the creped area, and are often colored unevenly, and flow marks areoften formed on their surface. In order that the moldings may have goodappearance and even gloss, the fragment (a) preferably has a relaxationtime, τ, of from 0.02 to 0.30 seconds, more preferably from 0.02 to 0.27seconds. To measure the relaxation time, τ, of the fragment (a),sinusoidal shear strain is imparted to a sample of the fragment (a) at atemperature of 175° C. and at an angular frequency, ω, of 10°/sec, usingRheometrics' System 4 (rotary rheometer with a cone plate of 25 mmφ anda cone angle of 0.1 radian), and the modulus of stored elasticity G' andthe modulus of loss elasticity G" of the sample are obtained. Therelaxation time, τ, of the sample is represented by t=G'/ωG".

The fragment (a) has a molecular weight distribution index (PDI) of from1 to 18, which is represented by ω₂ /10ω₁ where ω₁ indicates an angularfrequency at which the modulus of stored elasticity, G', as obtainedthrough melt viscoelastometry is 2×10² Pa, and ω₂ indicates an angularfrequency at which G' is 2×10⁴ Pa. Moldings comprising the component (A)of which the fragment (a) has PDI of larger than 18 will have bad weldappearance and uneven gloss in the creped area, and are often coloredunevenly. In order that the moldings may have good appearance and evengloss, the molecular weight distribution index (PDI) of the fragment (a)is preferably from 2 to 16, more preferably from 2 to 14. PDI of thefragment (a) is measured, using Rheometrics' System 4 (rotary rheometerwith a cone plate of 25 mmφ and a cone angle of 0.1 radian), at 175° C.and under strain of 30%.

The fragment (b) must have a limiting viscosity [η] (in decalin at 135°C.) of from 2.0 to 10 dl/g. Moldings comprising the component (A) ofwhich the fragment (b) has [η] of smaller than 2.0 dl/g will have badweld appearance and uneven gloss in the creped area; while thosecomprising the component (A) of which the fragment (b) has [η] of largerthan 10 dl/g will have flow marks as the moldability of the compositionis poor, and, in addition, they will have poor impact resistance. Inorder that the moldings may have good weld appearance, even gloss in thecreped area, and high impact resistance and that the composition mayhave good moldability, [η] of the fragment (b) is preferably from 2.2 to9.0 dl/g, more preferably from 2.4 to 8.0 dl/g.

In the second invention, in addition, the propylene-based resin of thecomponent (A) must have an ethylene unit content of from 1 to 17% byweight. If the content in question is smaller than 1% by weight, themoldings comprising the component (A) will have bad weld appearance,uneven gloss in the creped area, and poor impact resistance. If anadditional rubber component is added to the composition in order toimprove the impact resistance of the moldings of the composition, themoldings shall have poor scratch-whitening resistance. On the otherhand, if the ethylene unit content of the component (A) is larger than17% by weight, the moldings comprising the component (A) will have badweld appearance, uneven gloss in the creped area, and poor stiffness,and, in addition, flow marks will be formed on the moldings as themoldability of the composition is poor. In order that the moldings mayhave well-balanced properties of good weld appearance, even gloss in thecreped area, good impact resistance and high stiffness and that thecomposition may have good moldability, the ethylene unit content of thecomponent (A) is preferably from 4 to 17% by weight, more preferablyfrom 6 to 17% by weight.

In the first and second inventions (herein referred to as the presentinvention), preferably, the propylene-based resin of the component (A)has a melt index (MI) of from (1 to 100 g/10) min, when measured at atemperature of 230° C. and under a load of 2.16 kgf. If the component(A) has MI of smaller than 1 g/10 min, the composition comprising thecomponent (A) will have poor moldability as its fluidity is poor.However, if the component (A) has MI of larger than 100 g/10 min, themechanical properties of the moldings comprising the component (A) willbe bad. In view of the balance of the moldability of the composition andthe mechanical properties of the moldings, MI of the component (A) ispreferably from (5 to 70 g/10 min) more preferably from (10 to 40 g/10min.) MI of the component (A) is obtained according to JIS K-7210.Especially preferred is (a mixture of a propylene-based resin having MIof larger than 8 g/10 min and a propylene-based resin having MI ofsmaller than 5 g/10 min, in which the latter propylene-based resinhaving MI of smaller than 5 g/10 min is in an amount of from 5 to 30% byweight) as the mixture is molded into moldings having good impactresistance. In this mixture, however, if the amount of thepropylene-based resin having MI of smaller than 5 g/10 min is largerthan 30% by weight, the composition comprising the resin mixture willhave poor moldability and the moldings of the composition will have flowmarks on their surface.

The method of producing the propylene-based resin of the component (A)is not specifically defined, provided that it produces propylene-basedresins satisfying the requirements noted above, and various methods areemployable herein for producing the component (A). For example, theconstituent components which have been prepared separately may beblended to give the component (A); or, as will be mentioned below,monomers are polymerized in a multi-stage polymerization manner in thepresence of a catalyst system comprising (a) a solid component composedof (i) a solid catalyst component containing magnesium, titanium, ahalogen atom and an electron donor, and optionally (ii) a crystallinepolyolefin, (b) an organic aluminium compound, and (c) an ordinaryelectron-donating compound, to give a propylene-ethylene block copolymerof the component (A).

For the multi-stage polymerization to give the propylene-ethylene blockcopolymer of the component (A), for example, employable is the methodmentioned below.

In the catalyst system to be used for the multi-stage polymerization,the solid catalyst component (a) is composed of the solid catalystcomponent (i) containing magnesium, titanium, a halogen atom and anelectron donor, and optionally the component (ii) of crystallinepolyolefin. The solid catalyst component (a) can be prepared bycontacting a magnesium compound and a titanium compound with an electrondonor. For this, the halogen atom is in the magnesium compound and/orthe titanium compound in the form of a halide.

The magnesium compound may be a reaction product of a metal magnesium, ahalogen and/or a halogen-containing compound, and an alcohol.

The titanium compound may be any known one, but preferred is ahigh-halogen, titanium compound such as typically titaniumtetrachloride. One or more titanium compounds may be used either singlyor as combined.

The electron donor may be selected from the electron-donating compoundswhich will be mentioned hereinunder as examples of the component (c).

To prepare the solid catalyst component (i), employable are any knownmethods (see JP-A Sho-53-43094, Sho-55-135102, Sho-55-135103,Sho-56-18606, Sho-56-166205, Sho-57-63309, Sho-57-190004, Sho-57-300407,Sho-58-47003).

The crystalline polyolefin of the component (ii) which is optionallyused for preparing the solid component (a) includes those to be obtainedfrom C₂₋₁₀ α-olefins, such as polyethylene, polypropylene, polybutene-1,poly-4-methyl-1-pentene. Those crystalline polyolefins may be preparedby any known methods, for example, by pre-polymerizing propylene in thepresence of a combination of the solid catalyst component (i) notedabove, an organic aluminium compound and optionally an electron-donatingcompound (pre-polymerization method).

The aluminium compound of the component (b) may be represented by ageneral formula (I):

    AlR.sup.1.sub.p X.sub.3-p                                  (I)

wherein R1 represents an alkyl group having from 1 to 20 carbon atoms,or an aryl group having from 6 to 20 carbon atoms; X represents ahalogen atom; and p represents a number of from 1 to 3.

The catalyst system generally comprises an electron-donating compound asthe component (c). The electron-donating compound comprises any ofoxygen, nitrogen, phosphorus, sulfur and silicon atoms, and willbasically improve the stereospecificity of propylene polymers.

As the electron-donating compound, for example, preferably used areorganic silicon compounds, esters, ketones, ethers, thioethers, acidanhydrides, and acid halides.

As mentioned in detail hereinabove, Ziegler-type solid catalysts areused for the production of propylene polymers, for which use ofmetallocene catalysts is being specifically noted.

The propylene-based resin of the component (A) for use in the inventioncan be produced in various methods, for example, can be produced inmulti-stage polymerization using the catalyst system mentioned above. Inthe multi-stage polymerization, the order and the number of thepolymerization stages may be freely determined. For example, in theinitial polymerization (first-stage polymerization), propylene may behomo-polymerized or co-polymerized (for example, with ethylene and otherolefins in an amount of not larger than 2% by weight) to give acrystalline propylene-based polymer, and in the next, second-stage andlater steps, ethylene and propylene may be subjected to randomcopolymerization, or ethylene, propylene and other α-olefins andpolyenes may be subjected to random copolymerization.

For example, the components (a) to (c) are mixed in a predeterminedratio to give a catalyst system, and immediately after the preparationof the catalyst system, the monomers may be applied thereto to start thepolymerization of the monomers; or alternatively, after the catalystsystem is ripened for 0.2 to 3 hours, the monomers may be appliedthereto. After the polymerization, the reaction mixture maybepost-treated in any ordinary manner.

The resin composition of the present invention may comprise one or morepropylene-based resins of the component (A) either singly or ascombined.

The resin composition of the invention comprises, as the component (B),an ethylene-C₃₋₁₈ α-olefin copolymer. The ethylene-α-olefin copolymerhas a density of from 0.850 to 0.875 g/cm³. If its density is largerthan 0.875 g/cm³, the copolymer is not effective in improving the impactresistance of the moldings of the composition. In view of the stiffnessand the impact resistance of the moldings, the preferred range of thedensity of the copolymer is between 0.855 and 0.870 g/cm³. The copolymerhas a melt index (MI) of from 0.01 to 25 g/10 min. If its MI is smallerthan 0.01 g/10 min, the copolymer not effective in improving the impactresistance of the moldings of the composition, and the moldings willhave flow marks. If, however, the copolymer has MI of larger than 25g/10 min, the moldings comprising the copolymer will have uneven glossin the creped area and have poor impact resistance. In order that themoldings may have good impact resistance and even gloss and that thecomposition has good moldability, MI of the copolymer preferably fallsbetween (0.01 and 6 g/10 min,) more preferably between (0.01 and 1 g/10min). MI of the copolymer is measured at 190° C. and under a load of2.16 kgf.

The comonomers of the copolymer, C₃₋₁₈ α-olefins include, for example,linear x-olefins such as butene-1, pentene-1, hexene-1, octene-1,nonene-1, decene-1, dodecene-1; and branched α-olefins such as3-methylbutene-1,4-methylpentene-1. Of those, especially preferred arelinear C₄₋₁₀ α-olefins. One or more of these α-olefins can be usedeither singly or as combined. If desired, the copolymer may additionallycomprise a diene component of, for example, dicyclopentadiene,ethylidene-norbornene, 1,4-hexadiene, 1,9-decadiene, andvinyl-norbornene.

The α-olefin content of the ethylene-α-olefin copolymer of the component(B) is not specifically defined, and may be so determined that thedensity of the copolymer may fall the defined range. In general,however, the α-olefin content is preferably from 20 to 70% by weight.The ethylene-α-olefin copolymer must be prepared in the presence of ametallocene catalyst. So far as the copolymer has the properties definedabove, the method for producing the copolymer is not specificallydefined. As the metallocene catalyst, for example, employable is any ofsingle-site catalysts (SSC) and constrained geometric catalysts (CGC).Specific examples of such metallocene catalysts are disclosed in, forexample, JP-A Hei-6-192506, Hei-7-145298, Hei-7-18151, Hei-7-145272, andInternational Patent Laid-Open WO94/06859, and in JP-A Hei-5-43618,Hei-5-51414, International Patent Laid-Open WO96/04317, WO93/13140,WO91/04255, and WO91/04257. More concretely mentioned are transitionmetal complexes having a cyclopentadienyl, mono (di, tri, tetra orpenta) methylcyclopentadienyl or indenyl group. In their use inpolymerization, these metallocene catalysts are generally combined withalkylaluminoxanes or ionic compounds such as boron compounds.

One or more such ethylene-α-olefin copolymers of the component (B) maybe used either singly or as combined.

For the ethylene-α-olefin copolymers of the component (B) for use in theinvention, some commercial products are available, for example, ENGAGE(trade name of the Dow Chemical Co.) POEs sold by Dow Chemical Japan Co.Any of those commercially-available compounds are usable herein.

The resin composition of the present invention comprises a high-densitypolyethylene as the component (C). The high-density polyethylene is notspecifically defined, but generally used is one having a density of from0.93 to 0.97 g/cm³ and a melt index of from 0.5 to 10 g/10 min.

The composition further comprises talc as the component (D). In view ofthe physical properties of the moldings, such as stiffness, impactresistance, scratch-whitening resistance, weld appearance and gloss,preferred is talc grains having a mean grain size of from 1 to 8 μm anda mean aspect ratio of not smaller than 4. Especially preferred arethose as produced by mechanical grinding or gaseous stream grinding, inview of the physical properties and the stiffness of the moldings.

Regarding the amounts of the components constituting the resincomposition of the invention, the composition comprises from 42 to 95%by weight of the propylene-based resin of the component (A), from 1 to10% by weight of the ethylene-α-olefin copolymer of the component (B),from 2 to 18% by weight of the high-density polyethylene of thecomponent (C), and from 2 to 35% by weight of talc of the component (D),in which the sum of the components (B) and (C) falls between 3 and 23%by weight.

If the amount of the component (A) is smaller than 42% by weight, themoldings will have bad weld appearance and uneven gloss in the crepedarea. If so, in addition, the composition has poor moldability, and themoldings will have flow marks on their surface. On the other hand, ifthe amount of the component (A) is larger than 95% by weight, the impactresistance of the moldings will be poor. If the amount of the component(B) is smaller than 1% by weight, the component (B) will be ineffectivein improving the impact resistance of the moldings. However, if it islarger than 10% by weight, the scratch-whitening resistance of themoldings will be poor. If the amount of the component (C) is smallerthan 2% by weight, the component (C) will be ineffective in improvingthe scratch-whitening resistance of the moldings. However, if it islarger than 18% by weight, the moldings will have bad weld appearanceand uneven gloss in the creped area, and will have poor stiffness athigh temperatures. If the amount of the component (D) is larger than 35%by weight, the moldings will have bad weld appearance, poor impactresistance, and poor scratch-whitening resistance. If so, in addition,the composition will have poor moldability and the moldings will haveflow marks on their surface. If the sum of the components (B) and (C) issmaller than 3% by weight, the moldings will have poor impact resistanceand poor scratch-whitening resistance; but if it is larger than 23% byweight, the moldings will have bad weld appearance and uneven gloss inthe creped area, and have poor stiffness. In order that the moldings mayhave well-balanced, good properties of weld appearance, even gloss inthe creped area, impact resistance, scratch-whitening resistance andstiffness and that the composition may have better moldability, thepreferred range of each component constituting the composition is asfollows: The amount of the component (A) is from 58 to 85% by weight;that of the component (B) is from 2 to 8% by weight; that of thecomponent (C) is from 3 to 15% by weight; that of the component (D) isfrom 7 to 30% by weight; and the sum of the components (B) and (C) isfrom 6 to 19% by weight.

The resin composition of the invention may optionally contain variousknown additives such as pigment, nucleating agent, anti-aging agent,antioxidant, antistatic agent, flame retardant, dispersant, etc.

The method for producing the propylene-based resin composition of theinvention is not specifically defined. For example, the components (A),(B), (C) and (D) and optionally other additives may be melt-kneaded,using a single-screw extruder, a double-screw extruder, a Bumbury mixer,a kneader, a roll mixer or the like, to give the composition.

The automobile trim members of the invention are produced by molding thepropylene-based resin composition in any conventional injection-moldingmethods (including compressed injection-molding methods, vapor-blowinginjection-molding methods). The automobile trim members include, forexample, instrument panels, door trims, console boxes, etc.

Now, the invention is described in more detail hereinunder withreference to the following Examples, which, however, are not intended torestrict the scope of the invention.

The physical properties of the moldings produced and the isotacticpentad fraction of the propylene-based resins produced were obtainedaccording to the methods mentioned below.

(1) Izod Impact Strength

Test pieces of molding samples were tested according to JIS K7110 tomeasure the Izod impact strength thereof.

(2) Modulus of Bending Elasticity

Test pieces of molding samples were tested according to JIS K7203 tomeasure the modulus of bending elasticity thereof.

(3) Scratch-whitening Resistance

The creped area of each test piece of molding samples was rubbed withthe ridges on the edge of a ¥100 coin as pressed against it. The testpieces having been greatly scratched and whitened on the rubbed areawere evaluated bad (rank C); those having been somewhat scratched andwhitened thereon were evaluated acceptable (rank B); and those havingbeen scratched and whitened little were evaluated good (rank A).

(4) Surface Gloss

The surface gloss of the creped area of test pieces of molding sampleswas visually checked. The test pieces with great uneven gloss wereevaluated bad (rank C); those with some uneven gloss were evaluatedacceptable (rank B); and those with little uneven gloss were evaluatedgood (rank A).

(5) Isotactic Pentad Fraction

220 mg of a resin sample was put into a 10φ NMR test tube, to which wasadded 3 ml of 1,2,4-trichlorobenzene/heavy benzene (90/10 vol. %), andthe sample was dissolved in the solvent at 140° C. to give a uniformsolution. The solution was subjected to ¹³ C-NMR under the followingcondition.

Frequency: 45 MHz

Spectrum Width: 25000 Hz

Temperature: 130° C.

Pulse Width: 8 μsec

Pulse Repetition Interval: 4 sec

Number of Integration: 10000 times

The other properties of propylene-based resin samples prepared in thefollowing Examples were measured according to the methods mentionedherein.

1. Production of Propylene Block Copolymer (PP-2)

(1) Preparation of Magnesium Compound

A 500-liter glass reactor equipped with a stirrer was fully purged withnitrogen gas, and 97.2 kg of ethanol, 640 g of iodine and 6.4 kg ofmetal magnesium were put into the reactor and reacted therein whilebeing stirred under reflux to give a solid reaction product. Thereaction mixture containing this solid reaction product was dried underreduced pressure to obtain a magnesium compound (solid reactionproduct).

(2) Preparation of Solid Catalyst Component

30 kg of the magnesium compound (not ground) prepared in (1), 150 litersof pure heptane, 4.5 liters of silicon tetrachloride, and 4.3 liters ofdi-n-butyl phthalate were put into a 500-liter, three-neck glass flaskwhich had been fully purged with nitrogen gas. With stirring thecontents of the flask at 90° C., 144 liters of titanium tetrachloridewas added thereto, and reacted at 110° C. for 2 hours. The solid productformed was isolated, and washed with pure heptane at 80° C. Next, 228liters of titanium tetrachloride was added thereto, and reacted for 2hours at 110° C., and the resulting reaction product was fully washedwith pure heptane. Thus was obtained a solid catalyst component.

(3) Pre-treatment prior to Polymerization

230 liters of pure n-heptane was put into a 500-liter reactor equippedwith a stirrer, and 25 kg of the solid catalyst component obtained in(2) was added thereto. Next, 1.0 mol, relative to 1 mol of titanium inthe solid catalyst component, of triethylaluminium and 1.8 mols,relative to the same, of dicyclopentyldimethoxysilane were addedthereto. Next, propylene was introduced thereinto to be up to 0.3 kg/cm²G in terms of the propylene partial pressure, and reacted at 40° C. for4 hours. After the reaction, the thus-processed solid catalyst componentwas washed several times with n-heptane, and carbon dioxide was appliedthereto for 24 hours with stirring.

(4) Production of Propylene Block Copolymer (PP-2) throughPolymerization

In the first stage, the solid catalyst component having been processedin (3) was fed into a 200-liter polymerization reactor (first reactor)equipped with a stirrer, in an amount of 3 mmols/hr in terms of Ti ofthe component, along with 4.0 mmols/kg-PP of triethylaluminium and 0.4mmols/kg-PP of dicyclopentyldimethoxysilane, and propylene and ethylenewere copolymerized in this reactor at a temperature of 85° C. and undera pressure (total pressure) of 28 kg/cm² G, while the amount of ethyleneand that of hydrogen being fed into the reactor were controlled to makethe resulting copolymer have a predetermined ethylene content and apredetermined molecular weight. In this step, the amount oftriethylaluminium and that of dicyclopentyldimethoxysilane fed into thefirst reactor were related to the amount of the copolymer PP dischargedout of the reactor.

Next, the powder formed was continuously discharged out of the firstreactor, and transferred into a 200-liter polymerization reactor (secondreactor) equipped with a stirrer. The second reactor was run at atemperature of 70° C. and under a pressure (total pressure) of 15 kg/cm²G, and the amount of propylene, that of ethylene and that of hydrogenfed thereinto were controlled to obtain a copolymer having apredetermined composition and a predetermined molecular weight.

The powder formed was continuously discharged out of the second reactor,and granulated to obtain a propylene block copolymer (PP-2). This had anisotactic pentad fraction of 97.0% and a melt index of 13.

2. Production of Propylene Block Copolymer (PP-3)

(1) Preparation of Magnesium Compound

A 12-liter glass reactor equipped with a stirrer was fully purged withnitrogen gas, and about 4,860 g of ethanol, 32 g of iodine and 320 g ofmetal magnesium were put into the reactor and reacted therein whilebeing stirred under reflux to give a solid reaction product. Thereaction mixture containing this solid reaction product was dried underreduced pressure to obtain a magnesium compound (solid reactionproduct).

(2) Preparation of Solid Catalyst Component

160 g of the magnesium compound (not ground) prepared in (1), 800 ml ofpure heptane, 24 ml of silicon tetrachloride, and 23 ml of diethylphthalate were put into a 5-liter, three-neck glass flask which had beenfully purged with nitrogen gas. With stirring the contents of the flaskat 90° C., 770 ml of titanium tetrachloride was added thereto, andreacted at 110° C. for 2 hours. The solid product formed was isolated,and washed with pure heptane at 80° C. Next, 1220 ml of titaniumtetrachloride was added thereto, and reacted for 2 hours at 110° C., andthe resulting reaction product was fully washed with pure heptane. Thuswas obtained a solid catalyst component.

(3) Pre-treatment prior to Polymerization

230 liters of n-heptane was put into a 500-liter reactor equipped with astirrer, and 25 kg of the solid catalyst component obtained in (2) wasadded thereto. Next, 0.6 mols, relative to 1 mol of titanium in thesolid catalyst component, of triethylaluminium and 0.4 mols, relative tothe same, of cyclohexylmethyldimethoxysilane were added thereto. Next,propylene was introduced thereinto to be up to 0.3 kg/cm² G in terms ofthe propylene partial pressure, and reacted at 20° C. for 4 hours. Afterthe reaction, the thus-processed solid catalyst component was washedseveral times with n-heptane, and carbon dioxide was applied thereto for24 hours with stirring.

(4) Production of Propylene Block Copolymer (PP-3) throughPolymerization

In the first stage, the solid catalyst component having been processedin (3) was fed into a 200-liter polymerization reactor(homo-polymerization reactor) equipped with a stirrer, in an amount of 3mmols/hr in terms of Ti of the component, along with 0.50 mols/hr oftriethylaluminium and 50 mmols/hr of cyclohexylmethyldimethoxysilane,and propylene was polymerized in this reactor at a temperature of 85° C.and under a propylene partial pressure of 28 kg/cm² G, while hydrogengas was introduced thereinto so as to make the resulting polymer have apredetermined molecular weight.

Next, the powder formed was continuously discharged out of thehomo-polymerization reactor, and transferred into arandom-copolymerization reactor (second-stage reactor) similar to thehomo-polymerization reactor. To the second-stage reactor of therandom-copolymerization reactor, propylene and ethylene were fed andrandom-copolymerized therein at a temperature of 70° C. and under apressure of 15 kg/cm² G. In this stage, the amount of propylene and thatof ethylene fed to the reactor were controlled to obtain a copolymerhaving a predetermined ethylene content. The powder formed wascontinuously discharged out of the random copolymerization reactor, andgranulated to obtain a propylene block copolymer (PP-3). This had anisotactic pentad fraction of 94.0% and a melt index of 3.

EXAMPLES 1 TO 6, COMPARATIVE EXAMPLES 1 TO 6

Components (A) to (D), (A) of propylene-based resin (single substance orblended mixture), (B) of ethylene-α-olefin copolymer orethylene-propylene rubber, (C) of high-density polyethylene and (D) oftalc, of which the amounts and the properties are shown in Table 1 (theamounts of (A) to (D) are % by weight relative to 100% by weight of thetotal of (A) to (D)), were mixed with 0.2 parts by weight, relative to100 parts by weight of (A) to (D) combined, of a dispersant of magnesiumstearate and 1.3 parts by weight, relative to the same, of a dark graypigment (PP-DHH7343, trade name of a product of Dainichi Seika Co.), andkneaded in a double-screw kneader to prepare various molding materials.Each molding material was molded in an injection-molding machine at aresin temperature of 220° C. to produce test pieces (140×140×3 mm,creped sheets for trims). The physical properties of these test pieceswere measured, and the data obtained are shown in Table 1.

                                      TABLE 1                                     __________________________________________________________________________    Propylene-based Resin (A)                                                                                                     isotactic                          23° C. p-xylene-insoluble 23° C. p-xylene ethylene                                                         pentad                          amount  amount fragment soluble fragment content fraction                       polymer                                                                            wt. %                                                                             polymer                                                                            wt. %                                                                             wt. %                                                                              τ (sec)                                                                       PDI wt. %                                                                             [η]                                                                            (wt. %)                                                                           (%)                           __________________________________________________________________________      Ex. 1 PP-1 54 PP-3 15 86 0.47 38 14 3.9 8 95.6                                Ex. 2 PP-2 54 PP-3 15 88 0.26 10 12 3.3 7 96.7                                Ex. 3 PP-2 45 PP-3 15 88 0.26 10 12 3.4 7 96.6                                Ex. 4 PP-2 48 PP-3 15 91 0.26 10  9 3.3 7 96.7                                Ex. 5 PP-2 45 PP-3 20 88 0.27 10 12 3.4 7 96.3                                Ex. 6 PP-2 58 --  0 90 0.25 10 10 3.3 6 97.4                                  Comp. PP-4 54 PP-3 15 84 0.26 10 16 3.1 9 94.0                                Ex. 1                                                                         Comp. PP-2 54 PP-3 15 88 0.26 10 12 3.3 7 96.7                                Ex. 2                                                                         Comp. PP-4 45 PP-3 15 84 0.26 10 16 3.4 9 94.0                                Ex. 3                                                                         Comp. PP-4 48 --  0 85 0.25 10 15 3.1 9 94.0                                  Ex. 4                                                                         Comp. PP-2 58 PP-3 15 88 0.26 10 12 3.1 7 96.7                                Ex. 5                                                                         Comp. PP-2 57 --  0 90 0.25 10 10 3.3 6 97.4                                  Ex. 6                                                                       __________________________________________________________________________                      Component    Properties                                                       (C)                modulus of                                  high-density Component Izod impact bending scratch-                          Component (B) polyethylene, (D) strength elasticity whitening surface             compound                                                                           amount, wt. %                                                                        wt. %  talc, wt. %                                                                         (KJ/m)                                                                              (MPa) resistance                                                                         gloss                         __________________________________________________________________________      Ex. 1 LL-1 4  4 23 53 2720 A B (note 2)                                       Ex. 2 LL-1 4  4 23 45 2800 A A                                                Ex. 3 LL-1 2 15 23 38 2770 A B                                                Ex. 4 LL-1 4 10 23 60 2680 A B                                                Ex. 5 LL-1 2 10 23 47 2830 A B                                                Ex. 6 LL-1 4 15 23 58 2670 A B                                                Comp. Ex. 1 LL-1 4  4 23 62 2370 C A                                          Comp. Ex. 2 EPR 4  4 23 23 2780 B B                                           Comp. Ex. 3 LL-1 2 15 23 53 2370 B B                                          Comp. Ex. 4 LL-1 4 25 23 76 2160 B C                                          Comp. Ex. 5 LL-1 4  0 23 22 2870 C A                                          Comp. Ex. 6 -- 0 20 23 16 2950 A B to C                                     __________________________________________________________________________     (Note 1) Description of Components (A) to (D):                                PP1: Idemitsu Polypro J758H, trade name of a product of Idemitsu              Petrochemical Co.; having an isotactic pentad fraction of 96.0% and a mel     index of 11.                                                                  PP4: Idemitsu Polypro J762H, trade name of a product of Idemitsu              Petrochemical Co,; having an isotactic pentad fraction of 94.0%.              LL1: ethyleneoctene-1 copolymer, ENGAGE EG8180, trade name of a product o     Dow Chemical Japan Co.; having an octene1 content of 26 wt. %, MI of 0.6      g/10 min, and a density of 0.863 g/cm.sup.3.                                  EPR: ethylenepropylene rubber, EP02P, trade name of a product of Nippon       Synthetic Rubber Co.; having a propylene content of 26 wt. %, MI of 1.6       g/10 min, and a density of 0.860 g/cm.sup.3.                                  Highdensity Polyethylene: Idemitsu Polyethy 210J, trade name of a product     of Idemitsu Petrochemical Co.; having a density of 0.968 g/cm.sup.3, and      MI of 6.0 g/10 min.                                                           Talc: JM156, trade name of a product of Asada Flour Milling Co.; having a     mean grain size of 4.4 μm (as measured with a laser grain analyzer,        SALD2000A manufactured by Shimazu Seisakusho Co.).                            (Note 2) Regarding the surface gloss, the products of Example 1 were          evaluated as B, like those of Examples 3 to 6, but the former were            somewhat inferior to the latter.                                         

Industrial Applicability

The moldings of the propylene-based resin composition of the presentinvention have good impact resistance, good scratch-whiteningresistance, good appearance including weld appearance, and even gloss.As flat finishing of the moldings can be omitted, the production costsof the moldings can be reduced. The resin composition of the inventionis favorably used for producing automobile trim members.

The automobile trim members made from the resin composition of theinvention have good outward appearance including even gloss and weldappearance, and may be used without being coated with finish paint. Inaddition, they have good stiffness, impact resistance andscratch-whitening resistance. Therefore, the resin composition of theinvention is favorably used for producing automobile trim members suchas creped instrument panels.

We claim:
 1. A propylene-based resin composition comprising (A) from 42to 95% by weight of a propylene-based resin having an isotactic pentadfraction of at least 95%, (B) from 1 to 10% by weight of anethylene-C₃₋₁₈ α-olefin copolymer having a density of from 0.850 to0.875 g/cm³ and a melt index of from 0.01 to 25 g/10 min, and preparedin the presence of a metallocene catalyst, (C) from 2 to 18% by weightof a high-density polyethylene having a density of from 0.93 to 0.97g/cm³ and a melt index of from 0.5 to 10 g/10 min, and (D) from 2 to 35%by weight of talc, the total of the components (B) and (C) being from 3to 23% by weight.
 2. The propylene-based resin composition as claimed inclaim 1, wherein the component (A) satisfies the following requirements(1) to (4):(1) The propylene-based resin of (A) comprises (a) from 70 to98% by weight of a fragment insoluble in para-xylene at 23° C. and (b)from 2 to 30% by weight of a fragment soluble in para-xylene at 23° C.;(2) The fragment (a) has a relaxation time, τ, of from 0.01 to 0.35seconds at an angular frequency, ω, of 10°/sec as obtained through meltviscoelastometry, and has a molecular weight distribution index (PDI) offrom 1 to 18, which is represented by ω₂ /10ω₁ where ω₁ indicates anangular frequency at which the modulus of stored elasticity, G', asobtained through melt viscoelastometry is 2×10₂ Pa, and ω₂ indicates anangular frequency at which G' is 2×10⁴ Pa; (3) The fragment (b) has alimiting viscosity [η] in decalin at 135° C. of from 2.0 to 10 dl/g; and(4) The ethylene unit content of (A) is from 1 to 17% by weight.
 3. Thepropylene-based resin composition as claimed in claim 1, wherein theethylene-C₃₋₁₈ α-olefin copolymer of the component (B) has an α-olefincontent of from 20 to 70% by weight.
 4. An automobile trim member asproduced by injection-molding the propylene-based resin composition ofclaim
 1. 5. An automobile trim member as produced by injection-moldingthe propylene-based resin composition of claim
 3. 6. The propylene-basedresin composition as claimed in claim 2, wherein the ethylene-C₃ -C₁₈α-olefin copolymer of the component (B) has an α-olefin content of from20 to 70% by weight.
 7. An automobile trim member as produced byinjection-molding the propylene-based resin composition of claim
 2. 8.The propylene-based resin composition as claimed in claim 1, wherein thecomponent (A) has a melt index of from 1 to 100 g/10 min.
 9. Thepropylene-based resin composition as claimed in claim 8, wherein thecomponent (A) has a melt index of from 5 to 70 g/10 min.
 10. Thepropylene-based resin composition as claimed in claim 9, wherein thecomponent (A) has a melt index of from 10 to 40 g/10 min.
 11. Thepropylene-based resin composition as claimed in claim 1, wherein thecomponent (A) is a mixture of a propylene-based resin having a meltindex of larger than 8 g/10 min, and of from 5 to 30% by weight of saidmixture, of a propylene-based resin having a melt index of smaller than5 g/10 min.
 12. The propylene-based resin composition as claimed inclaim 1, wherein the component (B) has a density of from 0.855 to 0.870g/cm³.
 13. The propylene-based resin composition as claimed in claim 1,wherein the component (B) has a melt index of from 0.01 to 6 g/10 min.14. The propylene-based resin composition as claimed in claim 13,wherein the component (B) has a melt index of from 0.01 to 1 g/10 min.15. The propylene-based resin composition as claimed in claim 1, whereinthe talc is in the form of grains having a mean grain size of from 1 to8 μm and a mean aspect ratio of not smaller than 4.